Controlling the normal:ISO aldehyde ratio in a mixed ligand hydroformylation process

ABSTRACT

A method of controlling an in-series, multiple, e.g., two, reaction zone, hydroformylation process for producing normal (N) and iso (I) aldehydes at a N:I ratio, the process comprising contacting an olefinically unsaturated compound with synthesis gas and a catalyst comprising (A) a transition metal, e.g., rhodium, (B) an organobisphosphite ligand, and (C) an organomonophosphite ligand, the contacting conducted in first and subsequent reaction zone(s) and at hydroformylation conditions comprising a transition metal concentration in each zone, the method comprising decreasing the transition metal concentration in the first reaction zone to decrease the N:I ratio or increasing the transition metal concentration in the first reaction zone to increase the N:I ratio.

FIELD OF THE INVENTION

This invention relates to hydroformylation processes. In one aspect, theinvention relates to controlling the straight chain to branched isomerratio of a hydroformylation process which uses a transition metal, e.g.,rhodium, catalyst while in another aspect, the invention relates to sucha process in which the transition metal is solubilized using a mixtureof two phosphite ligands. In yet another aspect, the invention iscontrolling the straight chain to branched isomer ratio of the aldehydeproduct without destruction of the ligands.

BACKGROUND OF THE INVENTION

The variable normal (i.e., straight chain) to iso (i.e., branched) index(VNI) hydroformylation process (such as described in WO 2008/115740 A1)uses a mixture of two phosphite ligands to allow for an adjustableselectivity in the normal:iso aldehyde product mixture. In particularthe three component catalyst system uses a transition metal, typicallyrhodium (Rh), an organopolyphosphite ligand, typically anorganobisphosphite ligand (obpl), and an organomonophosphite ligand(ompl) in which the organomonophosphite ligand to rhodium (ompl:Rh)molar ratio is typically maintained in excess of five to 1 (>5:1) andthe organobisphosphite ligand to rhodium (obpl:Rh) molar ratio iscontrolled between 0 and 1:1 to control the N:I over the range whichwould be obtained based solely on an ompl:Rh molar ratio (typicallybetween 1 and 5) to that obtained for an obpl:Rh molar ratio (typicallybetween 20 and 40 for propylene). The conventional method of controllingN:I is to control the organobisphosphite ligand to rhodium ratio. Inparticular the method for lowering N:I is to lower the concentration ofthe organobisphosphite ligand through the natural decomposition of theligand through oxidation and hydrolysis. The difficulty with thismethod, however, is that it is slow, i.e., it takes time for the naturaldecomposition of the organobisphosphite ligand. Increasing the rate ofdecomposition of the organobisphosphite ligand is known, but this methodincreases the expense of the process. Of interest is a method forcontrolling N:I without decomposing the expensive organobisphosphiteligand.

BRIEF SUMMARY OF THE INVENTION

In one embodiment the invention is a method of controlling amulti-reaction zone hydroformylation process for producing normal (N)and iso (I) aldehydes at a N:I ratio, the process comprising contactingan olefinically unsaturated compound with carbon monoxide, hydrogen anda catalyst comprising (A) a transition metal, preferably rhodium, (B) anorganopolyphosphite, preferably an organobisphosphite, ligand and (C) anorganomonophosphite ligand, the contacting conducted in first andsubsequent reaction zones and at hydroformylation conditions comprisinga transition metal concentration in each zone, the method comprisingdecreasing the transition metal concentration in the first reaction zoneto decrease the N:I ratio or increasing the transition metalconcentration in the first reaction zone to increase the N:I ratio. Inone embodiment the transition metal concentration in the first reactionzone is decreased by removing transition metal into a storage zone. Inone embodiment the transition metal concentration in the first reactionzone is increased by adding fresh transition metal to the first reactionzone and/or transferring transition metal from the storage zone back tothe first reaction zone.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

All references to the Periodic Table of the Elements refer to thePeriodic Table of the Elements published and copyrighted by CRC Press,Inc., 2003. Also, any references to a Group or Groups shall be to theGroup or Groups reflected in this Periodic Table of the Elements usingthe IUPAC system for numbering groups. Unless stated to the contrary,implicit from the context, or customary in the art, all parts andpercents are based on weight and all test methods are current as of thefiling date of this disclosure. For purposes of United States patentpractice, the contents of any referenced patent, patent application orpublication are incorporated by reference in their entirety (or itsequivalent US version is so incorporated by reference) especially withrespect to the disclosure of synthetic techniques, definitions (to theextent not inconsistent with any definitions specifically provided inthis disclosure), and general knowledge in the art.

All percentages, preferred amounts or measurements, ranges and endpointsare inclusive, that is, “up to 10” includes 10. “At least” is equivalentto “greater than or equal to,” and “at most” is, thus, equivalent “toless than or equal to.” Numbers are approximate unless otherwisespecifically noted. All ranges from a parameter described as “at least,”“greater than,” “greater than or equal to” or similarly, to a parameterdescribed as “at most,” “up to,” “less than,” “less than or equal to” orsimilarly are preferred ranges regardless of the relative degree ofpreference indicated for each parameter. Thus a range that has anadvantageous lower limit combined with a most preferred upper limit ispreferred for the practice of this invention. The term “advantageous” isused to denote a degree of preference more than required, but less thanis denoted by the term “preferably.” Numerical ranges are providedwithin this disclosure for, among other things, the relative amount ofreagents and process conditions.

The hydroformylation process, its reagents, conditions and equipment,are well known and described in, among other references, U.S. Pat. Nos.4,169,861, 5,741,945, 6,153,800 and 7,615,645, EP 0590613 A2 and WO2008/115740 A1. Typically, an olefinically unsaturated compound, e.g.,propylene, is fed with synthesis gas, i.e., carbon monoxide (CO) andhydrogen (H₂), along with a three-component catalyst comprising atransition metal, preferably rhodium, and an organopolyphosphite,preferably an organobisphosphite, and an organomonophosphite ligand, thecontacting conducted at hydroformylation conditions into a multi-reactorsystem coupled in series, i.e., the output of the first reaction zone isfed as input to the subsequent reaction zone. The processing techniquescan correspond to any of the known processing techniques employed inconventional hydroformylation processes. For instance, the processes canbe conducted in either the liquid or gaseous states and in a continuous,semi-continuous or batch fashion and involve a liquid recycle and/or gasrecycle operation or a combination of such systems as desired. Likewise,the manner or order of addition of the reaction ingredients, catalystand solvent are also not critical and may be accomplished in anyconventional fashion.

Olefinically-unsaturated compounds suitably employed in the process ofthis invention are those that are capable of participating in ahydroformylation process to produce corresponding aldehyde product(s)and capable of being separated from the crude liquid hydroformylationproduct stream via vaporization. For the purposes of this invention, an“olefin” is defined as an aliphatic organic compound containing at leastcarbon and hydrogen atoms and having at least one carbon-carbon doublebond (C═C). Preferably, the olefin contains one or two carbon-carbondouble bonds, more preferably, one carbon-carbon double bond. The doublebond(s) can be located at a terminal position along the carbon chain(alpha olefin) or at any internal position along the chain (internalolefin). Optionally, the olefin can comprise elements other than carbonand hydrogen including, for example, nitrogen, oxygen, and halogens,preferably, chlorine and bromine. The olefin can also be substitutedwith functional substituents including, for example, hydroxy, alkoxy,alkyl and cycloalkyl substituents. Preferably, the olefin used in theprocess of this invention comprises a substituted or unsubstitutedolefin having a total of from 3 to 10 carbon atoms. Illustrative olefinssuitable for the process of this invention include, without limitation,isomers of the following mono-olefins of butene, pentene, hexene,heptene, octene, nonene and decene, with specific non-limiting examplesincluding 1-butene, 2-butene, 1-pentene, 2-pentene, and 1-hexene,2-hexene, 3-hexene, and similarly, for heptene, octene, nonene, anddecene. Other non-limiting examples of suitable olefins include 2-methylpropene(isobutylene), 2-methylbutene, cyclohexene, butadiene, isoprene,2-ethyl-1-hexene, styrene, 4-methyl styrene, 4-isopropyl styrene,4-tert-butyl styrene, alpha-methyl styrene, 3-phenyl-1-propene,1,4-hexadiene, 1,7-octadiene; as well as alkenols, for example,pentenols; alkenals, for example, pentenals; such species to includeally alcohol, allyl butyrate, hex-1-en-4-ol, oct-1-en-4-ol, vinylacetate, allyl acetate, 3-butenyl acetate, vinyl propionate, allylpropionate, methyl methacrylate, vinyl ethyl ether, vinyl methyl ether,allyl ethyl ether, 3-butenenitrile, 5-hexenamide, and dicyclopentadiene.The olefin can also be a mixture of olefins of similar or differentmolecular weights or structures (optionally with inerts such as thecorresponding saturated alkanes).

Preferably, the olefin stream used in the process of this inventioncomprises a C4 raffinate I or C4 raffinate II isomeric mixturecomprising butene-1, butene-2, isobutylene, butane, and optionally,butadiene. The C4 raffinate I stream comprises from 15 to 50 percentisobutylene and from 40 to 85 percent normal butenes, by weight, anyremainder to 100 percent comprising primarily n-butane and isobutane.The normal butenes are generally a mixture of butene-1 and butene-2(cis- and trans-forms). The relative proportions stream componentsdepend upon the composition of the petroleum feed, the conditionsemployed in steam cracking or catalytic cracking operation, and in thesubsequent process steps, from which the C4 stream is derived. The C4raffinate II stream comprises from 15 to 55 percent 1-butene, from 5 to15 percent 2-butene (5 to 35 percent trans-2-butene), from 0.5 to 5percent isobutylene, and from 1 to 40 percent butane, by volume. Morepreferably he olefin stream comprises propylene or mixtures of propyleneand propane and other inerts.

Hydrogen and carbon monoxide are also required for the hydroformylationstep of this invention. These gases can be obtained from any availablesource including petroleum cracking and refinery operations. Synthesisgas mixtures are preferably employed. The H₂:CO molar ratio of gaseoushydrogen to carbon monoxide can range, preferably, from 1:10 to 100:1,the more preferred H₂:CO molar ratio being from 1:10 to 10:1, and evenmore preferably, from 2:1 to 1:2. The gases are generally quantified bytheir partial pressures in the reactor based on their mole fraction inthe gas phase (as measured by gas chromatography) and the total pressureusing Dalton's Law. As used in the context of this invention, “syngaspartial pressure” is the sum of the partial pressure of CO and thepartial pressure of H₂.

Suitable metals that make up the transition metal-ligand complexcatalyst include Group VIII metals selected from rhodium (Rh), cobalt(Co), iridium (Ir), ruthenium (Ru), iron (Fe), nickel (Ni), palladium(Pd), platinum (Pt), osmium (Os) and mixtures of two or more of thesemetals, with the preferred metals being rhodium, cobalt, iridium andruthenium, more preferably rhodium, cobalt and ruthenium, and mostpreferably, rhodium. Other permissible metals include Group VIB metalsselected from chromium (Cr), molybdenum (Mo), tungsten (W), and mixturesof two or more of these metals. Mixtures of metals from Groups VIB andVIII may also be used in this invention.

“Complex” and like terms means a coordination compound formed by theunion of one or more electronically rich molecules or atoms (i.e.,ligand) with one or more electronically poor molecules or atoms (e.g.,transition metal). For example, the organomonophosphite ligand used inthe practice of this invention possesses one phosphorus (III) donor atomhaving one unshared pair of electrons, which is capable of forming acoordinate covalent bond with the metal. The organopolyphosphite ligandused in the practice of this invention possesses two or more phosphorus(III) donor atoms, each having one unshared pair of electrons, each ofwhich is capable of forming a coordinate covalent bond independently orpossibly in concert (for example, via chelation) with the transitionmetal. Carbon monoxide can also be present and complexed with thetransition metal. The ultimate composition of the complex catalyst mayalso contain an additional ligand, for example, hydrogen or an anionsatisfying the coordination sites or nuclear charge of the metal.Illustrative additional ligands include, for example, halogen (Cl, Br,I), alkyl, aryl, substituted aryl, acyl, CF₃, C₂F₅, CN, (R)₂PO andRP(O)(OH)O (in which each R is the same or different and is asubstituted or unsubstituted hydrocarbon radical, for example, alkyl oraryl), acetate, acetylacetonate, SO₄, PF₄, PF₆, NO₂, NO₃, CH₃O,CH₂═CHCH₂, CH₃CH═CHCH₂, C₂H₅CN, CH₃CN, _(NH3), pyridine, (C₂H₅)₃N,mono-olefin, diolefin and triolefin, tetrahydrofuran, and the like.

The number of available coordination sites on the transition metal iswell known in the art and depends upon the particular transition metalselected. The catalytic species may comprise a complex catalyst mixturein their monomeric, dimeric or higher nuclearity forms, which preferablyare characterized by at least one organophosphorus-containing moleculecomplexed per one molecule of metal, for example, rhodium. For instance,the catalytic species of the preferred catalyst employed in thehydroformylation reaction may be complexed with carbon monoxide andhydrogen in addition to either the organopolyphosphite ligand or theorganomonophosphite ligand.

The organopolyphosphite ligand broadly comprises a plurality ofphosphite groups, each of which contains one trivalent phosphorus atombonded to three hydrocarbyloxy radicals. Hydrocarbyloxy radicals thatlink and bridge two phosphite groups are more properly referred to as“divalent hydrocarbyldioxy radicals.” These bridging di-radicals are notlimited to any particular hydrocarbyl species. On the other hand,hydrocarbyloxy radicals that are pendant from a phosphorus atom and notbridging two phosphite groups (i.e., terminal, non-bridging), are eachrequired to consist essentially of an aryloxy radical. “Aryloxy” broadlyrefers to either of two types of aryloxy radicals: (1) a monovalent arylradical bonded to a single ether linkage, as in —O-aryl, wherein thearyl group comprises a single aromatic ring or multiple aromatic ringsthat are fused together, directly linked, or indirectly linked (suchthat different aromatic groups are bound to a common group such as amethylene or ethylene moiety), or (2) a divalent arylene radical bondedto two ether linkages, as in —O-arylene-O— or —O-arylene-arylene-O—, inwhich the arylene group comprises a divalent hydrocarbon radical havinga single aromatic ring or multiple aromatic rings that are fusedtogether, directly linked, or indirectly linked (such that the differentaromatic groups are bound to a common group such as a methylene orethylene moiety). Preferred aryloxy groups contain one aromatic ring orfrom 2 to 4 fused or linked aromatic rings, having from about 5 to about20 carbon atoms, for example, phenoxy, naphthyloxy, or biphenoxy, aswell as arylenedioxy radicals, such as, phenylenedioxy,naphthylenedioxy, and biphenylenedioxy. Any of these radicals and groupsmay be unsubstituted or substituted.

Preferred organopolyphosphite ligands comprise two, three or highernumbers of phosphite groups. Mixtures of such ligands may be employed ifdesired. Achiral organopolyphosphites are preferred. Representativeorganopolyphosphites include those of formula (I):

in which X represents a substituted or unsubstituted n-valent organicbridging radical containing from 2 to 40 carbon atoms, each R¹ is thesame or different and represents a divalent arylene radical containingfrom 6 to 40 carbon atoms, preferably, from 6 to 20 carbon atoms; eachR² is the same or different and represents a substituted orunsubstituted monovalent aryl radical containing from 6 to 24 carbonatoms; a and b can be the same or different and each has a value of 0 to6, with the proviso that the sum of a+b is 2 to 6 and n equals a+b. Whena has a value of 2 or more, each R¹ radical may be the same ordifferent, and when b has a value of 1 or more, each R² radical may bethe same or different.

Representative n-valent (preferably divalent) hydrocarbon bridgingradicals represented by X include both acyclic radicals and aromaticradicals, such as alkylene, alkylene-Qm-alkylene, cycloalkylene,arylene, bisarylene, arylene-alkylene, andarylene-(CH₂)_(y)-Q-(CH₂)_(y)-arylene radicals, wherein each y is thesame or different and is a value of 0 or 1. Q represents a divalentbridging group selected from —C(R³)₂—, —O—, —S—, —NR⁴—, —Si(R⁵)₂— and—CO—, wherein each R³ is the same or different and represents hydrogen,an alkyl radical having from 1 to 12 carbon atoms, phenyl, tolyl, andanisyl, R⁴ represents hydrogen or a substituted or unsubstitutedmonovalent hydrocarbon radical, for example, an alkyl radical having 1to 4 carbon atoms; each R⁵ is the same or different and representshydrogen or an alkyl radical, preferably, a C₁₋₁₀ alkyl radical, and mis a value of 0 or 1. The more preferred acyclic radicals represented byX above are divalent alkylene radicals while the more preferred aromaticradicals represented by X are divalent arylene and bisarylene radicals,such as disclosed more fully, for example, in U.S. Pat. Nos. 4,769,498;4,774,361; 4,885,401; 5,179,055; 5,113,022; 5,202,297; 5,235,113;5,264,616; 5.364,950; 5,874,640; 5,892,119; 6,090,987; and 6,294,700.

Illustrative preferred organopolyphosphites include bisphosphites suchas those of formulae (II) to (IV):

in which R¹, R² and X of formulae (II) to (IV) are the same as definedabove for formula (I). Preferably X represents a divalent hydrocarbonradical selected from alkylene, arylene, arylene-alkylene-arylene, andbisarylene; R¹ represents a divalent hydrocarbon radical selected fromarylene, arylene-alkylene-arylene, and bisarylene; and each R² radicalrepresents a monovalent aryl radical. Organopolyphosphite ligands ofsuch formulae (II) to (IV) may be found disclosed, for example, in U.S.Pat. Nos. 4,668,651; 4,748,261; 4,769,498; 4,774,361; 4,885,401;5,113,022; 5,179,055; 5,202,297; 5,235,113; 5,254,741; 5,264,616;5,312,996 and 5,364,950.

Representative of more preferred classes of organobisphosphites arethose of the formulae (V) to (VII).

in which Q, R¹, R², X, m, and y are as defined above, and each Ar is thesame or different and represents a substituted or unsubstituted divalentaryl radical. Most preferably, X represents a divalentaryl-(CH₂)_(y)-(Q)_(m)-(CH₂)_(y)-aryl radical wherein each yindividually has a value of 0 or 1; m has a value of 0 or 1 and Q is—O—, —S— or —C(R³)₂ where each R³ is the same or different andrepresents hydrogen or a C₁₋₁₀ alkyl radical, preferably, methyl. Morepreferably, each aryl radical of the above-defined AR, X, R¹ and R²groups of formulae (V) to (VII) may contain 6 to 18 carbon atoms and theradicals may be the same or different, while the preferred alkyleneradicals of X may contain 2 to 18 carbon atoms. In addition, preferablythe divalent Ar radicals and divalent aryl radicals of X of the aboveformulae are phenylene radicals in which the bridging group representedby —(CH₂)_(y)-(Q)_(m)-(CH₂)_(y)— is bonded to the phenylene radicals inpositions that are ortho to the oxygen atoms of the formulae thatconnect the phenylene radicals to their phosphorus atom. Any substituentradical when present on such phenylene radicals is preferably bonded inthe para and/or ortho position of the phenylene radicals in relation tothe oxygen atom that bonds the given substituted phenylene radical toits phosphorus atom.

Moreover, if desired any given organopolyphosphite in the above formulae(I) to (VII) may be an ionic phosphite, that is, may contain one or moreionic moieties selected from the group consisting of —SO₃M, wherein Mrepresents an inorganic or organic cation, —PO₃M wherein M represents aninorganic or organic cation, —N(R⁶)3X¹, wherein each R⁶ is the same ordifferent and represents a hydrocarbon radical containing from 1 to 30carbon atoms, for example, alkyl, aryl, alkaryl, aralkyl, and cycloalkylradicals, and X¹ represents inorganic or organic anion, —CO₂M wherein Mrepresents inorganic or organic cation, as described, for example, inU.S. Pat. Nos. 5,059,710; 5,113,022; 5,114,473 and 5,449,653. Th us, ifdesired, such organopolyphosphite ligands may contain from 1 to 3 suchionic moieties; however, preferably only one such ionic moiety issubstituted on any given aryl moiety when the organopolyphosphite ligandcontains more than one such ionic moiety. Suitable cationic species of Minclude, without limitation, hydrogen (i.e., a proton), the cations ofthe alkali and alkaline earth metals, for example, lithium, sodium,potassium, cesium, rubidium, calcium, barium, magnesium and strontium,the ammonium cation and quaternary ammonium cations, phosphoniumcations, arsonium cations and iminium cations. Suitable anions X¹include, for example, sulfate, carbonate, phosphate, chloride, acetate,oxalate and the like.

Of course any of the R¹, R², X, Q and Ar radicals of such non-ionic andionic organopolyphosphites of formulae (I) to (VII) above may besubstituted if desired, with any suitable substituent, optionallycontaining from 1 to 30 carbon atoms, that does not adversely affect thedesired result of the process of this invention. Substituents that maybe on the radicals in addition, of course, to corresponding hydrocarbonradicals such as alkyl, aryl, aralkyl, alkaryl and cyclohexylsubstituents, may include for example silyl radicals such as —Si(R⁷)₃;amino radicals such as —N(R⁷)₂; phosphine radicals such as -aryl-P(R⁷)₂;acyl radicals such as —C(O)R⁷; acyloxy radicals such as —OC(O)R⁷; amidoradicals such as —CON(R⁷)₂ and —N(R⁷)COR⁷; sulfonyl radicals such as—SO₂R⁷, alkoxy radicals such as —OR⁷; sulfinyl radicals such as —SOR⁷;sulfenyl radicals such as —SR⁷; phosphonyl radicals such as —P(O)(R⁷)₂;as well as halogen, nitro, cyano, trifluoromethyl, hydroxy radicals, andthe like, wherein preferably each R⁷ radical individually represents thesame or different monovalent hydrocarbon radical having from 1 to about18 carbon atoms (for example, alkyl, aryl, aralkyl, alkaryl andcyclohexyl radicals) with the proviso that in amino substituents such as—N(R⁷)₂ each R⁷ taken together can also represent a divalent bridginggroup that forms a heterocyclic radical with the nitrogen atom, and inamido substituents such as —C(O)N(R⁷)₂ and —N(R⁷)COR⁷ each R⁷ bonded toN can also be hydrogen. Of course any of the substituted orunsubstituted hydrocarbon radicals groups that make up a particulargiven organopolyphosphite may be the same or different.

More specifically illustrative substituents include primary, secondaryand tertiary alkyl radicals such as methyl, ethyl, n-propyl, isopropyl,butyl, sec-butyl, t-butyl, neopentyl, n-hexyl, amyl, sec-amyl, t-amyl,iso-octyl, decyl, octadecyl, and the like; aryl radicals such as phenyland naphthyl; aralkyl radicals such as benzyl, phenylethyl, andtriphenylmethyl; alkaryl radicals such as tolyl and xylyl; alicyclicradicals such as cyclopentyl, cyclohexyl, 1-methylcyclohexyl,cyclo-octyl, and cyclohexylethyl; alkoxy radicals such as methoxy,ethoxy, propoxy, t-butoxy, —OCH₂CH₂OCH₃, —O(CH₂CH₂)₂OCH₃, and—O(CH₂CH₂)₃OCH₃; aryloxy radicals such as phenoxy; as well as silylradicals such as —Si(CH₃)₃, —Si(OCH₃)₃, and —Si(C₃H₇)₃; amino radicalssuch as —NH₂, —N(CH₃)₂, —NHCH₃, and —NH(C₂H₅); arylphosphine radicalssuch as —P(C₆H₅)₂; acyl radicals such as —C(O)CH₃, —C(O)C₂H₅, and—C(O)C₆H₅; carbonyloxy radicals such as —C(O)OCH₃; oxycarbonyl radicalssuch as —O(CO)C₆H₅; amido radicals such as —CONH₂, —CON(CH₃)₂, and—NHC(O)CH₃; sulfonyl radicals such as —S(O)₂C₂H₅; sulfinyl radicals suchas —S(O)CH₃; sulfenyl radicals such as —SCH₃, —SC₂H₅, and —SC₆H₅;phosphonyl radicals such as —P(O)(C₆H₅)₂, —P(O)(CH₃)₂, —P(O)(C₂H₅)₂,—P(O)(C₃H₇)₂, —P(O)(C₄H₉)₂, —P(O)(C₆H₁₃)₂, —P(O)CH₃(C₆H₅). and—P(O)(H)(C₆H₅).

Specific examples of organobisphosphites are Ligands A-S of WO2008/115740.

The organomonophosphites that can be used in the practice of thisinvention include any organic compound comprising one phosphite group. Amixture of organomonophosphites can also be used. Representativeorganomonophosphites include those of formula (VIII).

in which R⁸ represents a substituted or unsubstituted trivalenthydrocarbon radical containing 4 to 40 carbon atoms or greater, such astrivalent acyclic and trivalent cyclic radicals, e.g., trivalentalkylene radicals such as those derived from 1,2,2-trimethylolpropane,or trivalent cycloalkylene radicals, such as those derived from1,3,5-trihydroxycyclohexane. Such organomonophosphites may be founddescribed in greater detail, for example, in U.S. Pat. No. 4,567,306.

Representative diorganophosphites include those of formula (IX).

in which R⁹ represents a substituted or unsubstituted divalenthydrocarbon radical containing 4 to 40 carbon atoms or greater and Wrepresents a substituted or unsubstituted monovalent hydrocarbon radicalcontaining 1 to 18 carbon atoms.

Representative substituted and unsubstituted monovalent hydrocarbonradicals represented by W in formula IX include alkyl and aryl radicals,while representative substituted and unsubstituted divalent hydrocarbonradicals represented by R⁹ include divalent acyclic radicals anddivalent aromatic radicals. Illustrative divalent acyclic radicalsinclude, for example, alkylene, alkylene-oxy-alkylene,alkylene-NX²-alkylene, wherein X² is hydrogen or a substituted orunsubstituted hydrocarbon radical, alkylene-S-alkylene, andcycloalkylene radicals. The more preferred divalent acyclic radicals arethe divalent alkylene radicals, such as disclosed more fully, forexample, in U.S. Pat. Nos. 3,415,906 and 4,567,302. Illustrativedivalent aromatic radicals include, for example, arylene bisarylene,arylene-alkylene, arylene-alkylene-arylene, arylene-oxy-arylene,arylene-NX²-arylene, wherein X² is as defined above, arylene-S-arylene,and arylene-S-alkylene. More preferably, R⁹ is a divalent aromaticradical, such as disclosed more fully, for example, in U.S. Pat. Nos.4,599,206 and 4,717,775.

Representative of a more preferred class of diorganomonophosphites arethose of formula (X).

in which W is as defined above, each Ar is the same or different andrepresents a substituted or unsubstituted divalent aryl radical, each yis the same or different and is value of 0 or 1, Q represents a divalentbridging group selected from) —C(R¹⁰)₂—, —O—, —S—, —NR¹¹—, —Si(R¹²)₂—and —CO, in which each R^(1°) is the same or different and representshydrogen, alkyl radicals having from 1 to 12 carbon atoms, phenyl,tolyl, and anisyl, R¹′ represents hydrogen or an alkyl radical of from 1to 10 carbon atoms, preferably, methyl, each R¹² is the same ordifferent and represents hydrogen or an alkyl radical having 1 to 10carbon atoms, preferably, methyl, and m is a value of 0 or 1. Suchdiorganomonophosphites are described in greater detail, for example, inU.S. Pat. Nos. 4,599,206, 4,717,775 and 4,835,299.

Representative triorganomonophosphites include those of formula (XI).

in which each R¹³ is the same or different and is a substituted orunsubstituted monovalent hydrocarbon radical, for example, an alkyl,cycloalkyl, aryl, alkaryl, or aralkyl radical, which may contain from 1to 24 carbon atoms. Illustrative triorganomonophosphites include, forexample, trialkylphosphites, dialkylarylphosphites,alkyldiarylphosphites, and triarylphosphites, such as,triphenylphosphite, tris(2,6-triisopropyl)phosphite,tris(2,6-di-tert-butyl-1-4-methoxyphenyl)phosphite, as well as the morepreferred tris(2,4-di-tert-butylphenyl)phosphite. The monovalenthydrocarbon radical moieties themselves may be functionalized with theproviso that the functional groups do not significantly interact withthe transition metal or otherwise inhibit hydroformylation.Representative functional groups include alkyl or aryl radicals, ethers,nitriles, amides, esters, —N(R¹¹)₂, —Si(R¹²)₃, phosphates, and the like,in which R¹¹ and R¹² are as previously defined. Suchtriorganomonophosphites are described in more detail in U.S. Pat. Nos.3,527,809 and 5,277,532.

As a further option any organomonophosphite-monophosphate ligand ororganomonophosphite-polyphosphate ligand may be employed as theorganomonophosphite ligand in this invention. For example, any of theorganopolyphosphite ligands, including preferred organobisphosphiteligands as previously described, may be subjected to oxidation such thatall but one of the phosphorus (III) atoms is converted into phosphorus(V) atoms. The resulting oxidized ligand can comprise anorganomonophosphite-polyphosphate or, preferably, anorganomonophosphite-monophosphate, which suitably is employed in a 2/1molar excess relative to the transition metal so as to provide for theorganomonophosphite ligand component used in the practice of thisinvention. As here used “organomonophosphite ligand” and like termsinclude organomonophosphite-monophosphate ligand andorganomonophosphite-polyphosphate ligand (as appropriate to the text inwhich the term is used) unless specifically noted otherwise.

As a further option any organomonophosphoramidite ligand can be used as,or in combination with, the organomonophosphite ligand used in thepractice of this invention, and any organopolyphosphoramidite ligand canbe used as, or in combination with, the organopolyphosphite ligand usedin the practice of this invention. Organophosphoramidite ligands areknown, and they are used in the same manner as organophosphite ligands.Representative organophosphoramidite ligands are of formulae (XII-XIV).

Organophosphoramidites are further described in, for example, U.S. Pat.No. 7,615,645. As here used “organomonophosphite ligand” and like termsinclude organomonophosphoramidite ligands unless specifically notedotherwise, and “organopolyphosphite ligand” and like terms includeorganopolyphosphoramidite ligands unless specifically noted otherwise.

The hydroformylation catalyst comprises a stabilized complex of (A)transition metal carbonyl hydride; (B) organobisphosphite ligand whichis provided in the catalyst system at concentrations up to and includinga 1:1 molar basis with respect to the transition metal component of thestabilized catalyst complex; and (C) monodentate phosphite ligand (i.e.,an organomonophosphite) which is provided in excess molar quantity withrespect to the rhodium metal component of the stabilized catalystcomplex.

The catalyst can be prepared in situ in a hydroformylation reaction zoneor, alternatively, it can be prepared ex-situ and subsequentlyintroduced into the reaction zone with the appropriate hydroformylationreactants. In one embodiment the catalyst is prepared by admixing onemole of suitable transition metal source with 0.1 to 1 mole oforganobisphosphite ligand and between 5-100 moles of monodentatephosphite ligand. In one embodiment the catalyst is prepared by admixingat a ratio of one mole of a suitable rhodium source to 5-100 moles ofthe monodentate phosphite ligand and after initiation of thehydroformylation reaction, the bisphosphite ligand (<1 mole) is added.

The catalytic species may comprise a complex catalyst mixture in itsmonomeric, dimeric or higher nuclearity forms which preferably arecharacterized by at least one organophosphorus-containing moleculecomplexed per one molecule of transition metal. For instance, thetransition metal may be complexed with carbon monoxide and hydrogen inaddition to either a monodentate phosphite ligand or a bisphosphiteligand.

The catalyst and its preparation are more fully described in U.S. Pat.Nos. 4,169,861, 5,741,945, 6,153,800 and 7,615,645, and WO 2008/115740.

The hydroformylation catalysts may be in homogeneous or heterogeneousform during the reaction and/or during the product separation. Theamount of metal-ligand complex catalyst present in the reaction mediumneed only be that minimum amount necessary to catalyze the process. Ifthe transition metal is rhodium, then concentrations in the range of 10to 1000 parts per million (ppm), calculated as free rhodium, in thehydroformylation reaction medium is sufficient for most processes, whileit is generally preferred to employ from 10 to 500 ppm rhodium, and morepreferably from 25 to 350 ppm rhodium.

In addition to the metal-ligand complex catalyst, free ligand (i.e.,ligand that is not complexed with the metal) may also be present in thehydroformylation reaction medium. The free ligand, mono- or polydentate,is preferably, but not necessarily, the same as the ligand of themetal-ligand complex catalyst employed. The hydroformylation process ofthis invention may involve from 0.1 moles or less to 100 moles orhigher, of free ligand per mole of metal in the hydroformylationreaction medium. Preferably the hydroformylation process is carried outin the presence of from 1 to 50 moles of ligand, and more preferablyfrom 1.1 to 4 moles of ligand, per mole of metal present in the reactionmedium; the amounts of ligand being the sum of both the amount of ligandthat is bound (complexed) to the metal present and the amount of free(non-complexed) ligand present. Of course, if desired, make-up oradditional ligand can be supplied to the reaction medium of thehydroformylation process at any time and in any suitable manner, e.g. tomaintain a predetermined level of free ligand in the reaction medium.

As a general procedure, the catalyst system is first formed in adeoxygenated solvent medium in a hydroformylation reaction zone. Excessmonodentate ligand can perform as the solvent medium. The firsthydroformylation zone is pressured with hydrogen and carbon monoxide andheated to a selected reaction temperature. The olefinically unsaturatedcompound is fed to the first hydroformylation zone, and the reaction isconducted until the desired conversion yield and efficiency have beenattained at which time the product of the first reaction zone istransferred to the subsequent reaction zone(s) in which fresh and/orrecycled reagents are added. The reaction in this subsequent reactionzone(s) continues until the desired conversion yield and efficiency areattained at which time the product of the last reaction zone isrecovered and purified. In a continuous system the catalyst ispreferably recycled back to the first reaction zone.

The reaction conditions of the hydroformylation process can vary widely.For instance, the H₂:CO molar ratio of gaseous hydrogen to carbonmonoxide advantageously can range from 1:10 to 100:1 or higher, the morepreferred hydrogen to carbon monoxide molar ratio being from 1:10 to10:1. Advantageously, the hydroformylation process can be conducted at areaction temperature greater than −25° C., more preferably, greater than50° C. The hydroformylation process advantageously can be conducted at areaction temperature less than 200° C., preferably, less than 120° C.Advantageously, the total gas pressure comprising olefinic reactant,carbon monoxide, hydrogen, and any inert lights can range from 1 psia(6.9 kPa) to 10,000 psia (68.9 MPa). Preferably, the process be operatedat a total gas pressure comprising olefinic reactant, carbon monoxide,and hydrogen of less than 2,000 psia (13,800 kPa), and more preferably,less than 500 psia (3450 kPa). Advantageously, the carbon monoxidepartial pressure varies from 1 psia (6.9 kPa) to 1000 psia (6,900 kPa),and preferably from 3 psia (20.7 kPa) to 800 psia (5,516 kPa), and morepreferably, from 15 psia (103.4 kPa) to 100 psia (689 kPa); while thehydrogen partial pressure varies preferably from 5 psia (34.5 kPa) to500 psia (3,450 kPa), and more preferably from 10 psia (69 kPa) to 300psia (2,070 kPa).

The feed flow rate of synthesis gas (CO+H₂) can vary widely over anyoperable flow rate sufficient to obtain the desired hydroformylationprocess. The syngas feed flow rate depends upon the specific form ofcatalyst, olefin feed flow rate, and other operating conditions.Likewise, the vent flow rate from the Oxo reactor(s) can be any operableflow rate sufficient to obtain the desired hydroformylation process.Vent flow rate is dependent upon the scale of the reactor and the purityof the reactant and syngas feeds. Suitable syngas feed flow rates andvent flow rates are well known or easily calculated by those skilled inthe art. In one embodiment the H₂ and CO partial pressures arecontrolled such that the reaction is conducted under conditions in whichthe hydroformylation rate is positive order for syngas (H₂ and CO)partial pressures for the monophosphite catalyst and negative order forthe CO partial pressure for the bisphosphite catalysts (such asdescribed in WO 2008/115740 A1).

Inert solvent can be employed as a hydroformylation reaction mediumdiluent. A variety of solvents can be used including ketones such asacetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, andcyclohexanone; aromatics such as benzene, toluene and xylenes;halogenated aromatics including o-dichlorobenzene; ethers such astetrahydrofuran, dimethoxyethane and dioxane; halogenated paraffinsincluding methylene chloride; paraffinic hydrocarbons such as heptane;and the like. The preferred solvent is the aldehyde product and/or theoligomers of the aldehyde product along with the reactive olefin orolefins.

In one embodiment the hydroformylation process is carried out in amulti-staged reactor such as described in U.S. Pat. No. 5,763,671. Suchmulti-staged reactors can be designed with internal, physical barriersthat create more than one theoretical reactive stage or zone per vessel.The effect is like having a number of reactors inside a singlecontinuous stirred tank reactor vessel. Multiple reactive stages withina single vessel are a cost effective way of using the reactor vesselvolume. It significantly reduces the number of vessels that otherwiseare required to achieve the same results. Obviously, however, if thegoal is to have different partial pressures of a reactant in differentstages of the process, then two or more reactors or vessels areemployed. Reaction zones can be in parallel or series but mostpreferably are in series.

The hydroformylation process of this invention is typically conducted ina two-stage, continuous manner. Such processes are well known in the artand may involve: (a) hydroformylating the olefinic starting material(s)with carbon monoxide and hydrogen in a liquid homogeneous reactionmixture comprising a solvent, the metal-phosphite ligand complexcatalyst, free phosphite ligand; (b) maintaining reaction temperatureand pressure conditions favorable to the hydroformylation of theolefinic starting material(s); (c) supplying make-up quantities of theolefinic starting material(s), carbon monoxide and hydrogen to thereaction medium as those reactants are used up; and (d) recovering thedesired aldehyde hydroformylation product(s) in any manner desired. Thecontinuous process can be carried out in a single pass mode in which avaporous mixture comprising unreacted olefinic starting material(s) andvaporized aldehyde product is removed from the liquid reaction mixturefrom whence the aldehyde product is recovered and make-up olefinicstarting material(s), carbon monoxide and hydrogen are supplied to theliquid reaction medium for the next single pass without recycling theunreacted olefinic starting material(s). Such types of recycle procedureare well known in the art and may involve the liquid recycling of themetal-phosphite complex catalyst fluid separated from the desiredaldehyde reaction product(s), such as disclosed in U.S. Pat. No.4,148,830 or a gas recycle procedure such as disclose in U.S. Pat. No.4,247,486, as well as a combination of both a liquid and gas recycleprocedure if desired. The most preferred hydroformylation process ofthis invention comprises a continuous liquid catalyst recycle process.Suitable liquid catalyst recycle procedures are disclosed, for example,in U.S. Pat. Nos. 4,668,651; 4,774,361; 5,102,505 and 5,110,990. Withmultiple reactor vessels, they can be run in series or in parallel (formixtures of both schemes).

In one embodiment the invention is to divert a portion (up to 50%) ofthe recycled catalyst from the product separation zone (such as avaporizer) from the first reaction zone to subsequent reaction zones.This reduces the amount of transition metal, e.g., rhodium, catalystpresent in the first reaction zone, and thus lowers the conversion ofolefin, e.g., propylene, by approximately the same percentage ofcatalyst diverted, e.g., up to 50%, in the first reaction zone, andincreases the amount of olefin, e.g., propylene, going into subsequentreaction zones. These subsequent reaction zones are operating at lowerolefin partial pressures which favor the monophosphite ligand catalystreactivity which exhibits lower N:I performance. The net N:I ratio ofthe final product is thus lowered. The higher catalyst concentration inthe subsequent reaction zones helps minimize efficiency loss. Inaddition the subsequent reactors can be operated at conditions thatfurther favor the monophosphite ligand (e.g., high syngas partialpressure). Conversely, reducing the amount of transition metal catalystdiverted from the first reaction zone will increase the N:I ratio of thefinal product.

In one embodiment the N:I ratio is lowered by adding fresh transitionmetal without any bisphosphite ligand to the first reactor. This can beaccomplished by adding the transition metal catalyst precursor (e.g.,Rh(acac)(CO)₂)or preformed monophosphite-metal complex). This has theimmediate effect of lowering the relative amount of obpl:metal complexin the system. The amount of change in the N:I ratio is readilycalculated by the relationship between the two metal-ligand complexes bythe ratio of the mole average rates as described above. The change inthe N:I ratio is typically 2-20 units to a minimum based on the N:Iratio of the metal-monodentate ligand catalyst alone.

In one embodiment the N:I ratio is lowered by removing some of thecatalyst (specifically some of the metal), e.g., up to 20%, from thefirst reaction zone into a storage zone, e.g., storage tank. This lowersthe conversion of propylene by approximately the same percentage ofcatalyst removed, e.g., up to 20%, in the first reaction zone, andincreases the amount of propylene going into subsequent reaction zones.These subsequent reaction zones are operating at lower olefin partialpressures which favor the monophosphite ligand catalyst thus exhibitlower N:I performance. The net N:I ratio of the final product is thuslowered. While the reduction in total catalyst from the system mayimpact olefin conversion efficiency, this can be overcome by running thesubsequent reaction zones at conditions that increase reaction rate(e.g., higher temperature, syngas pressures, etc.) which will enhancethe amount of product generated under the low N:I ratio conditions. Inaddition the subsequent reactors can be operated at conditions thatfurther favor the monophosphite ligand (e.g., high syngas partialpressure). Conversely, returning the catalyst back into the system willincrease the N:I ratio of the final product. The catalyst can be removedeither by removing it from the first or subsequent reaction zones orfrom the catalyst recycle stream returning from the product separationzone. The removed catalyst is typically stored in a separate storagevessel free of air (oxygen) at reduced temperature.

A further embodiment of the invention related to the previousembodiments involves the condition of the catalyst that has been removedfrom the first reaction zone. Upon storage, this isolated catalystcontinues to have normal ligand decomposition and the obpl:metal ratiowill change with time. The obpl:metal ratio will be lower than when itwas removed and if the original obpl:metal ratio has been maintained (orincreased) in the reaction zones since this portion of catalyst wasremoved, the addition of this isolated catalyst will reduce the N:Iratio. The amount of change can be predicted by measuring the N:I ratioof the stored catalyst or by 31P NMR (looking for conversion ofcomplexed bisphosphite to its corresponding decomposition products), andthen determining the new obpl:metal ratio would be upon addition basedon the models described above.

Still a further embodiment of the invention is a hydroformylationprocess in which (A) the catalyst comprises (1) a transition metal,preferably rhodium, (2) an organopolyphosphoramidite, preferably anorganobisphosphoramidite, ligand, and (3) an organomonophosphite ligand,(B) the organomonophosphite ligand transition metal ratio is maintainedat a greater than 2:1 molar excess, and (C) the N:I ratio is controlledby adjusting the amount of organopolyphosphoramidite relative to theamount of transition metal in the process. The steps of this processinclude (a) measuring the N:I ratio of the hydroformylation product, and(b) adjusting the concentration of the organopolyphosphoramidite ligandto raise or lower the product N:I.

The measurement of the hydroformylation product N:I ratio can be made bya variety of methods. One example is analysis of either vapor or liquidstreams coming from the reactors or process streams. Quick methods suchas gas chromatography (GC), infrared (IR) or nuclear infrared (NIR) canbe used. The product N/I can also be determined by flow measurementsfrom the distillation column used to separate the normal and branchedproducts.

An increase in organopolyphosphoramidite ligand concentration up to 1:1phosphoramidite:transition metal molar ratio raises the N:I ratio. Thiscan be achieved by incremental additions in batches or a continuous feedof ligand as either a solid or solutions of the solid, preferably wherethe product aldehyde is used as the solvent. In this manner, a controlloop is established where the ligand feed rate is coupled to andcontrolled by the output from the product N/I.

A decrease in organopolyphosphoramidite ligand below a 1:1phosphoramidite:transition metal molar ratio lowers the hydroformylationproduct N:I ratio. Phosphoramidite decomposition is inherent to theprocess, and thus the phosphoramidite concentration decreases whichresults in a drop of N/I ratio over time. This natural slow and steadyreduction is the preferred method for removal of the phosphoramidite. Ifa more rapid decrease in the product N/I ratio is desired, then adecrease in phosphoramidite concentration can be accomplished byincreasing the rate of its decomposition. One method by which this canbe accomplished is by increasing the rate of hydrolysis using anextractor system to control phosphoramidite hydrolysis and removephosphoramidite decomposition products. Simply lowering the pH of theaqueous phase of the extractor will result in an increased rate ofhydrolysis of phosphoramidite.

An alternative method to decrease the hydroformylation product N:I ratiois simply to raise the reactor temperatures which in turn increase thenatural rate of phosphoramidite decomposition. Phosphoramiditeconcentration can also be reduced by oxidation to its monophosphate anddiphosphate forms.

Additional reduction in variability in product rate is also obtained bycontrolling the relative concentration of the organopolyphosphoramiditeligand up to a 1:1 molar ratio to transition metal. The aldehyde productrate in this region is inversely proportional to phosphoramiditeconcentration. Higher phosphoramidite concentrations result in loweraldehyde rates.

Operation of a stable variable N:I process with a catalyst comprising atransition metal, particularly rhodium, and a mixed ligand system oforganopolyphosphoramidite and organomonophosphite also has the advantageof reducing catalyst cost relative to a catalyst comprising a transitionmetal and a triphenylphosphine ligand (a commercially usedhydroformylation catalyst). In the latter case, if the transition metalis rhodium (the most commonly used), then the concentration of rhodiumis typically 200-300 ppm. The rhodium concentration in the mixed ligandprocess of this embodiment is 20-50 ppm—a 5 to 10 fold decrease in thecost of an extremely expensive precious metal.

The transition metal/mixed ligand catalyst systems of this embodimentallow variation in the N:I ratio of 2:1 to 100:1 if the olefin ispropylene, and of 2:1 to 1,000:1 if the olefin is butene.

Specific Embodiments

General Procedure for Hydroformylation Process

The hydroformylation process is conducted in a glass pressure reactoroperating in a continuous mode. The reactor consists of a three ouncepressure bottle partially submersed in an oil bath with a glass frontfor viewing. After purging the system with nitrogen, about 20-30milliliters (mL), preferably 20 mL, of a freshly prepared rhodiumcatalyst precursor solution is charged to the reactor with a syringe.The catalyst precursor solution contains 50-200 ppm rhodium, preferably100 ppm, (introduced as rhodium dicarbonyl acetylacetonate), Ligand 1,and tetraglyme as solvent. After sealing the reactor, the system ispurged with nitrogen and the oil bath is heated to furnish the desiredhydroformylation reaction temperature, preferably 80° C. The catalystsolution is activated with a feed of 1:1 CO and H2 at a total operatingpressure of 150 to 160 psig (1034 to 1103 kPa) for 30 to 60 minutes, andat a temperature ranging from 50 to 100° C. After the activation period,the reaction is initiated by the introduction of propylene. Flows of theindividual gases are adjusted as desired, and nitrogen is added asnecessary to maintain the desired total operating pressure of about 150psig (1034 kPa). The flows of the feed gases (H₂, CO, propylene, N₂) arecontrolled individually with mass flow meters and the feed gases aredispersed in the catalyst precursor solution via fritted metal spargers.The partial pressures of N₂, H₂, CO, propylene, and aldehyde productsare determined by analyzing the vent stream by GC analysis and Dalton'sLaw. The unreacted portion of the feed gases is stripped out withbutyraldehydes products by the nitrogen flow to maintain substantiallyconstant liquid level. Flows and feed gas partial pressures are set toobtain hydroformylation reaction rates of around 1 gram-moles aldehydeper liter reaction fluid per hour. The outlet gas is analyzedcontinuously by gas chromatography (GC). Samples of the reaction fluidare withdrawn (via syringe) for ³¹P NMR to determine the rate ofdecomposition of the ligands as a function of time under the reactionconditions. In practice, it is often observed that the system takesabout one day to arrive at steady state conditions due to removing traceair from feed lines and reaching thermal equilibration of oil baths; soligand decomposition studies are only initiated after steady stateoperations are achieved. This equipment also allows generatinghydroformylation rates as a function of reaction temperature, CO and H₂partial pressures, and Rh content.

The reaction system is initiated with the rhodium-organomonophosphitecatalyst to establish a preliminary steady state operation and then theN/I isomer ratio is adjusted to the desired target ratio by slowlyadding the bisphosphoramidite ligand. The bisphosphoramidite ligand(Ligand 2) and the organomonophosphite ligand (Ligand 1) are shownbelow.

EXAMPLE 1 Butyraldehyde with a N:I Ratio Less than 10

Catalyst solution is prepared and charged to the glass reactor system.Conditions are established as described below:

Ligand 1 (wt %) 0.47 Rhodium (ppm) 75 Hydrogen (psig) 42 CO (psig) 42Propylene (psig) 4 Temperature (° C.) 75 Total Pressure (psig) 150

After several days of hydroformylation with Rh/Ligand 1, small portionsof Ligand 2 are added from a toluene stock solution. Because smallamounts of ligand are often decomposed by oxygen, water and othercontaminants in the system, the ligand is added slowly while monitoringthe N/I ratio. An average of 0.12 equivalents per day of Ligand 2 perrhodium is added over 10 days, over which time the aldehyde N:I ratio isabout 2. The subsequent addition of an aliquot of Ligand 2 (0.14equivalents per rhodium) results in an increase of the aldehyde N:Iratio to about 7.

EXAMPLE 2 Butyraldehyde with a N:I Ratio of 30

A catalyst solution is prepared and charged to the glass reactor systemas described in Example 1. After several days of hydroformylation withRh/Ligand 1, small portions of Ligand 2 are added from a toluene stocksolution. An average of 0.27 equivalents per day of Ligand 2 per rhodiumis added over three days, over which time the aldehyde N:I ratio isabout 2. The subsequent addition of an aliquot of Ligand 2 (0.4equivalents per rhodium) results in an increase in the aldehyde N:Iratio to about 32.

EXAMPLE 3 Butyraldehyde with a N:I Ratio of 40

A catalyst solution is prepared and charged to the glass reactor systemas described in Example 1. After several days of hydroformylation withRh/Ligand 1 at an aldehyde N:I ratio of about 2, small portions ofLigand 2 are added from a toluene stock solution. An aliquot of 0.80equivalents of Ligand 2 per rhodium is added on the first day, afterwhich subsequent additions of Ligand 2 result in a significant change inthe N/I ratio. The subsequent addition of an aliquot of Ligand 2 (0.4equivalents per rhodium) results in an increase of the aldehyde N:Iratio to about 40. After an additional one-half day, an additionalaliquot of Ligand 2 is added (0.2 equivalents per rhodium) which resultsin an increase in the aldehyde N:I ratio to over 50. No further Ligand 2is added, and over the next day the aldehyde N:I ratio steadily lowersto under 5 due to gradual decomposition of Ligand 2.

EXAMPLE 4 Butyraldehyde with a N:I Ratio of 16

The average decomposition rate of Ligand 2 (0.14 equivalents per day),and the relationship between Ligand 2 concentration and N:I ratio can becalculated based on Examples 1-3. Based on these results, the effectiveaddition of 0.20 equivalents of Ligand 2 per rhodium should produce analdehyde N:I ratio of about 16. A catalyst solution is prepared andcharged to the glass reactor system as described in Example 1. Afterseveral days of hydroformylation with Rh/Ligand 1, small portions ofLigand 2 are added from a toluene stock solution. An average of 0.14equivalents per day of Ligand 2 per rhodium are added over 7 days,during which time the aldehyde N:I ratio is about 2. The subsequentaddition of an aliquot of Ligand 2 (0.2 equivalents per rhodium) resultsin an increase in the aldehyde N/I ratio to about 19.

EXAMPLE 5 Varying the N:I Ratio Based on Additional Rhodium

Catalyst solution consisting of Rh(CO)2(acac) (100 ppm Rh), Ligand 1 (10equivalents per rhodium) and tetraglyme (20 mL) is prepared and chargedto the glass reactor system. Conditions are established as describedbelow:

Rhodium (ppm) 100 Hydrogen (psig) 48-52 CO (psig) 48-52 Propylene (psig)1-3 Oil Bath Temperature (° C.)  80 Nitrogen Pressure balance

Small aliquots (0.3 to 0.8 equivalents per rhodium) of Ligand 2 is addedto increase the N:I. Once a consistent high N:I is established, analiquot of fresh rhodium is added via syringe (25 ppm rhodium asRh(CO)2(acac) dissolved in toluene), and the resulting change indetermined. Then sufficient time is allowed for the system to fullypurge and reach a steady state following each addition (10-16 hours).The rhodium addition is repeated and the N:I is determined. A time linefrom 0-72 hours is shown below indicating the corresponding N:I ratios.

Time Action (hrs) N:I 0 0.6 1 0.7 2 0.8 3 0.9 4 1.1 5 1.1 6 1.0 7 1.0 81.0 9 1.0 10 1.0 11 1.0 12 1.0 13 1.0 14 1.0 15 1.0 16 1.0 17 1.0 18 1.019 1.0 Add 0.8 eq Ligand 2 20 1.0 21 1.3 22 1.7 23 2.0 24 2.1 25 2.2 262.2 27 2.2 28 2.2 29 2.2 Add 0.3 eq Ligand 2 30 2.0 31 3.0 32 5.3 33 8.934 9.0 35 7.4 36 6.3 37 5.7 38 5.3 40 5.1 41 4.9 42 4.8 43 4.7 Add 0.3eq of Ligand 2 44 4.5 45 0.7 46 10.1 47 14.7 48 19.8 49 23.8 50 26.9 5131.1 52 31.3 53 33.5 Add 25 ppm Rh 54 30.0 55 15.1 56 8.6 57 6.7 58 6.159 5.8 60 5.6 61 5.5 62 5.3 63 5.2 64 5.1 66 5.1 67 5.0 Add 25 ppm Rh 684.9 69 2.5 70 2.0 71 1.9 72 2.0

Example 5 demonstrates that the normal to isoaldehyde ratio can belowered rapidly and effectively by adding additional fresh rhodium tothe rhodium-organomonophosphite and bisphosphoramidite catalyst system.

Although the invention has been described in considerable detail by thepreceding specification, this detail is for the purpose of illustrationand is not to be construed as a limitation upon the following appendedclaims.

What is claimed is:
 1. A method of controlling a multi-reaction zone,hydroformylation process for producing normal (N) and iso (I) aldehydesat a N:I ratio, the process comprising contacting an olefinicallyunsaturated compound with carbon monoxide, hydrogen and a catalystcomprising (A) a transition metal, (B) an organopolyphosphite ligand(obpl), and (C) an organomonophosphite ligand, the contacting conductedin first and one or more subsequent reaction zones and athydroformylation conditions comprising a metal concentration and aobpl:metal ratio in each zone, the process further comprising a productseparation zone from which catalyst is recovered and recycled, themethod comprising changing the transition metal concentration in thefirst reaction zone by one or more of the following methods: 1.Partitioning the catalyst recycle from the product separation zonebetween the first reaction zone and one or more subsequent reactionzones; or
 2. Decreasing the obpl:metal ratio by adding transition metalwithout any organobisphosphite ligand either as a transition metalprecursor or a metal-organomonophosphite compound; or
 3. Decreasing thetransition metal concentration in the first reaction zone by removing upto 20% of the transition metal catalyst from the reaction system into aseparate vessel; or
 4. Returning transition metal catalyst removed inoption (C) to the first reaction zone.
 2. The method of claim 1 in whichthe transition metal concentration in the first reaction zone isdecreased by removing transition metal into a storage zone.
 3. Themethod of claim 1 in which the transition metal concentration in thefirst reaction zone is increased by adding fresh transition metal to thefirst reaction zone and/or transferring transition metal from thestorage zone back to the first reaction zone.
 4. The method of claim 1in which the olefinically unsaturated compound is an olefin having atotal of from 3 to 10 carbon atoms.
 5. The method of claim 1 in whichthe olefinically unsaturated compound is a C₄ raffinate I or C₄raffinate II isomeric mixture comprising butene-1, butene-2,isobutylene, butane, and optionally, butadiene.
 6. The method of claim 1in which the syngas comprises carbon monoxide and hydrogen at a H₂:COmolar ratio of 10:1 to 1:10.
 7. The method of claim 1 in which thecatalyst comprises a stabilized complex of (A) rhodium carbonyl hydride;(B) organobisphosphite ligand which is provided in the catalyst systemat concentrations up to a 1:1 molar basis with respect to the rhodiummetal component of the stabilized catalyst complex; and (C)organomonophosphite ligand which is provided in excess molar quantitywith respect to the rhodium metal component of the stabilized catalystcomplex.
 8. The method of claim 1 in which the catalyst is prepared byadmixing at a ratio of one mole of a rhodium source to 5-100 moles ofthe organomonophosphite ligand and after initiation of thehydroformylation reaction, adding 0.1 to less than one mole of theorganobisphosphite ligand.
 9. The method of claim 6 in which theorganomonophosphite ligand is of the formula

and the organobisphosphite ligand is of the formula


10. The method of claim 1 in which the hydroformylation conditionsinclude a reaction temperature greater than −25° C. and less than 200°C., and a total gas pressure comprising olefinic reactant, carbonmonoxide, hydrogen, and any inert lights of 1 psia (6.8 kPa) to 10,000psia (68.9 MPa).
 11. A method of controlling a multi-reaction zone,hydroformylation process for producing normal (N) and iso (I) aldehydesat a N:I ratio, the process comprising contacting an olefinicallyunsaturated compound with carbon monoxide, hydrogen and a catalystcomprising (A) a transition metal, (B) an organopolyphosphoramidite, and(C) an organomonophosphite ligand, the contacting conducted in first andone or more subsequent reaction zones and at hydroformylation conditionscomprising an organomonophosphite ligand to transition metal molar ratiogreater than 2:1, the method comprising the steps of (1) measuring theN:I ratio of the hydroformylation product, and (2) adjusting theconcentration of the organopolyphosphoramidite ligand up to a 1:1organophosphoramidite to transition metal ratio to raise or lower theproduct N:I.
 12. The method of claim 11 in which the transition metal isrhodium, the organopolyphosphoramidite is an organobisphosphoramidite,and the olefinically unsaturated compound is propylene or butene. 13.The method of claim 12 in which the organobisphosphoramidite is of theformula


14. The method of claim 13 in which the concentration of theorganopolyphosphoramidite ligand is raised relative to the measured N:Iratio of the hydroformylation product.
 15. The method of claim 13 inwhich the concentration of the organopolyphosphoramidite ligand islowered relative to the measured N:I ratio of the hydroformylationproduct.